Thermography camera tuned to detect absorption of infrared radiation in a selected spectral bandwidth

• US 9,635,284 B2
• Filed: 02/29/2016
• Issued: 04/25/2017
• Est. Priority Date: 03/23/2007
• Status: Active Grant

• Current Assignee: Teledyne FLIR LLC (Teledyne Technologies Incorporated)
• Original Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Inventors: Benson, Robert G., Scanlon, Thomas J., Czerepuszko, Paul A.
• Primary Examiner(s): Bryant, Casey
• Application Number:
  US15/056,960
• Publication Number:
  US 20160255284A1
• Time in Patent Office: 421 Days
• CPC Class Codes: G01J 2005/0077 Imaging
• CPC Class Codes: G01J 2005/123 Thermoelectric array
• CPC Class Codes: G01J 3/0286 Constructional arrangements for compensating for fluctuations caused by temperature, humidity or pressure, or using cooling or temperature stabilization of parts of the device; Controlling the atmosphere inside a spectrometer, e.g. vacuum
• CPC Class Codes: G01J 3/2803 using photoelectric array detector
• CPC Class Codes: G01J 5/06 Arrangements for eliminating effects of disturbing radiation; Arrangements for compensating changes in sensitivity for adjusting of solid angle of collected radiation G01J5/07; means for wavelength selection G01J5/0801
• CPC Class Codes: G01J 5/061 by controlling the temperature of the apparatus or parts thereof, e.g. using cooling means or thermostats
• CPC Class Codes: G01J 5/0802 Optical filters
• CPC Class Codes: G01J 5/0806 Focusing or collimating elements, e.g. lenses or concave mirrors
• CPC Class Codes: G01J 5/12 using thermoelectric elements, e.g. thermocouples
• CPC Class Codes: G01J 5/48 Thermography; Techniques using wholly visual means
• CPC Class Codes: G01N 2021/1793 Remote sensing
• CPC Class Codes: G01N 2021/3531 without instrumental source, i.e. radiometric
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis
• CPC Class Codes: G01N 21/3518 Devices using gas filter correlation techniques; Devices using gas pressure modulation techniques
• CPC Class Codes: H01L 31/03042 characterised by the doping material
• CPC Class Codes: H01L 31/03046 including ternary or quaternary compounds, e.g. GaAlAs, InGaAs, InGaAsP
• CPC Class Codes: H01L 31/035236 Superlattices; Multiple quantum well structures
• CPC Class Codes: H01L 31/18 Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
• CPC Class Codes: H04N 23/54 Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

An infrared camera system is provided to detect absorption of infrared radiation in a selected spectral bandwidth. In one example, an infrared camera system includes a lens adapted to receive infrared radiation from a survey scene comprising one or more gasses. The infrared camera system also includes a focal plane array comprising a plurality of quantum well infrared photo detectors (QWIPs). The QWIPs are tuned to detect a limited spectral bandwidth of the infrared radiation corresponding to at least a portion of an infrared absorption band of the one or more gasses. The infrared camera system also includes an optical band pass filter positioned substantially between the lens and the focal plane array. The optical band pass filter is adapted to filter the infrared radiation to a wavelength range substantially corresponding to the limited spectral bandwidth of the QWIPs before the infrared radiation is received by the focal plane array.

Claims

1. A device comprising:

a focal plane array comprising a plurality of infrared photo detectors, wherein each infrared photo detector comprises;

a plurality of quantum well layers configured to generate a desired photocurrent in response to infrared radiation; and

a plurality of barrier layers alternating with the quantum well layers,

wherein an amount of doping of the quantum well layers, a spacing of quantum wells in the quantum well layers, and thicknesses of the quantum well layers and the barrier layers are selected to tune the focal plane array to have a limited spectral bandwidth with a peak response within a wavelength range of 10.3 μ

m to 10.8 μ

m and a full width half maximum spectral bandwidth of less than 0.7 μ

m in response to the infrared radiation, and

wherein the less than 0.7 μ

m spectral bandwidth of the focal plane array is selected to reduce signal noise substantially outside the wavelength range of 10.3 μ

m to 10.8 μ

m associated with operation of the focal plane array and/or an optical band pass filter.

2. The device of claim 1, further comprising the optical band pass filter.

3. The device of claim 2, wherein the optical band pass filter is positioned substantially between a survey scene emitting the infrared radiation and the focal plane array and is adapted to filter the infrared radiation to a wavelength range substantially corresponding to the limited spectral bandwidth of the focal plane array before the infrared radiation is received by the focal plane array.

4. The device of claim 1, further comprising a lens positioned substantially between a survey scene emitting the infrared radiation and the focal plane array, wherein the lens is adapted to focus the infrared radiation at a focal plane substantially coincident with the focal plane array.

5. The device of claim 1, further comprising a processor coupled to the focal plane array, wherein:

the focal plane array is adapted to provide a plurality of signals in response to the infrared radiation;

the less than 0.7 μ

m spectral bandwidth of the focal plane array is selected to reduce dark current associated with the focal plane array and/or the optical band pass filter; and

the processor is adapted to receive the plurality of signals and render an image of a survey scene emitting the infrared radiation.

6. The device of claim 5, further comprising an output port coupled to the processor and adapted to pass the image to an external device.

7. The device of claim 5, further comprising a display coupled to the processor and adapted to display the image to a user.

8. The device of claim 5, wherein:

the image comprises a rendering of one or more gasses in the survey scene having at least one absorption band within the limited spectral bandwidth of the focal plane array.

9. The device of claim 8, wherein the one or more gasses include a gas leak plume or a gas identified in TABLE 2.

10. A method of manufacturing a device, the method comprising:

forming a focal plane array comprising a plurality of infrared photo detectors, wherein;

the plurality of infrared photo detectors comprises a plurality of quantum well layers configured to generate a desired photocurrent in response to infrared radiation and a plurality of barrier layers alternating with the quantum well layers,

an amount of doping of the quantum well layers, a spacing of quantum wells in the quantum well layers, and thicknesses of the quantum well layers and the barrier layers are selected to tune the focal plane array to have a limited spectral bandwidth with a peak response within a wavelength range of 10.3 μ

m to 10.8 μ

m and a full width half maximum spectral bandwidth of less than 0.7 μ

m in response to the infrared radiation, and

the less than 0.7 μ

m spectral bandwidth of the focal plane array is selected to reduce signal noise substantially outside the wavelength range of 10.3 μ

m to 10.8 μ

m associated with operation of the focal plane array and/or an optical band pass filter.

11. The method of claim 10, further comprising providing the optical band pass filter, wherein the optical band pass filter is positioned substantially between a survey scene emitting the infrared radiation and the focal plane array and is adapted to filter the infrared radiation to a wavelength range substantially corresponding to the limited spectral bandwidth of the focal plane array before the infrared radiation is received by the focal plane array.

12. The method of claim 11, wherein the optical band pass filter comprises a longwave band pass filter adapted to filter out infrared radiation outside of a longwave infrared spectrum.

13. The method of claim 10, further comprising providing a lens positioned substantially between a survey scene emitting the infrared radiation and the focal plane array, wherein the lens is adapted to focus the infrared radiation at a focal plane substantially coincident with the focal plane array.

14. The method of claim 10, further comprising providing a processor coupled to the focal plane array, wherein:

the focal plane array is adapted to provide a plurality of signals in response to the infrared radiation;

the less than 0.7 μ

m spectral bandwidth of the focal plane array is selected to reduce dark current associated with the focal plane array and/or the optical band pass filter; and

the processor is adapted to receive the plurality of signals and render an image of a survey scene emitting the infrared radiation.

15. The method of claim 14, further comprising providing an output port coupled to the processor and adapted to pass the image to an external device.

16. The method of claim 14, further comprising providing a display coupled to the processor and adapted to display the image to a user.

17. The method of claim 14, wherein:

the image comprises a rendering of one or more gasses in the survey scene having at least one absorption band within the limited spectral bandwidth of the focal plane array.

18. The method of claim 17, wherein the one or more gasses include a gas leak plume or a gas identified in TABLE 2.

19. A method of providing an image of a survey scene, the method comprising:

receiving infrared radiation from the survey scene at a focal plane array comprising a plurality of infrared photo detectors adapted to receive the infrared radiation, wherein;

the plurality of infrared photo detectors comprises a plurality of quantum well layers configured to generate a desired photocurrent in response to the infrared radiation and a plurality of barrier layers alternating with the quantum well layers,

an amount of doping of the quantum well layers, a spacing of quantum wells in the quantum well layers, and thicknesses of the quantum well layers and the barrier layers are selected to tune the focal plane array to have a limited spectral bandwidth with a peak response within a wavelength range of 10.3 μ

m to 10.8 μ

m and a full width half maximum spectral bandwidth of less than 0.7 μ

m in response to the infrared radiation, and

the less than 0.7 μ

m spectral bandwidth of the focal plane array is selected to reduce signal noise substantially outside the wavelength range of 10.3 μ

m to 10.8 μ

m associated with operation of the focal plane array and/or an optical band pass filter; and

providing a plurality of signals from the focal plane array corresponding to an image of the survey scene.

20. The method of claim 19, further comprising filtering the infrared radiation to a filtered wavelength range substantially corresponding to the limited spectral bandwidth of the focal plane array, by the optical band pass filter, before the infrared radiation is received by the focal plane array.